4. Cannabis the drug

4.4 Routes of administration

Almost all possible routes of administration have been used, but by far the most common method is smoking (inhaling). Marijuana is most often smoked as a hand-rolled "joint" the size of a cigarette or larger, and usually thicker. Tobacco is often added to marijuana to assist burning and "make it go further", and a filter may be inserted. Hashish may be mixed with tobacco and smoked as a joint, but is more often smoked through a pipe, either with or without tobacco. A water pipe known as "bong" is a popular implement for all cannabis preparations, because the water cools the hot smoke before it is inhaled and there is little loss of the drug through sidestream smoke. Hash oil is used sparingly because of its extremely high psychoactive potency; a few drops may be applied to a cigarette or a joint, to the mixture in the pipe, or the oil may be heated and the vapours inhaled. Whatever method is used, smokers usually inhale deeply and hold their breath for several seconds in order to ensure maximum absorption of THC by the lungs.

Hashish may also be cooked or baked in foods and eaten. When ingested orally the onset of the psychoactive effects is delayed by about an hour. In clinical and experimental research, THC has often been prepared in gelatine capsules and administered orally. In India, a popular method of ingestion is in the form of a tea-like brew of the leaves and stems, known as "bhang". The "high" is of lesser intensity but the duration of intoxication is longer by several hours. It is easier to titrate the dose and achieve the desired level of intoxication by smoking than by oral ingestion since the effects are more immediate.

Crude aqueous extracts of cannabis have on very rare occasions been injected intravenously. THC is insoluble in water, so little or no drug is actually present in these extracts, and the injection of tiny
undissolved particles may cause severe pain and inflammation at the site of injection and a variety of toxic systemic effects. Injection should not be considered as a route of cannabis administration, but
has been used in research to investigate pharmacokinetics.

Since different routes of administration give rise to differing pharmacokinetics, the reader should assume for the remainder of this document that the method of ingestion is smoking unless stated otherwise.